Vascular access catheters can be used for hemodialysis, a medical procedure used to cleanse the blood of patients whose kidneys do not function properly, by simultaneously extracting and returning fluids to the patient's body. Dual or triple lumen hemodialysis catheters have two or three longitudinal lumens extending the length of the catheter. In dual lumen hemodialysis catheters, one lumen can be dedicated for withdrawal of blood to be cleansed, known as the arterial or aspiration lumen, and another lumen can be dedicated for return of the cleansed blood to the central circulatory system. This lumen is also known as the venous or return lumen. The distal segment of the catheter is typically positioned at the junction of the superior vena cava and right atrium to obtain a blood flow of sufficient volume to accommodate dialysis treatment requirements. These and other types of multilumen catheters are typically constructed of two or more catheter tubes of the same shape, color, and a single thermoplastic material such as polyurethane. Such catheters can be extruded and then bonded together using chemicals, solvents, or adhesives to form a unitary catheter shaft for at least a portion of the overall catheter length. The chemicals, solvents, or adhesives can be placed along at least a partial or a complete length of the catheter tube surfaces in order to secure the tubes together. Outer sleeves can be used to hold multiple catheter tubes together around at least a portion of an exterior surface of multiple catheter tubes, such that at least a portion of the catheter tubes are fixed within the outer sleeve. Extrusion is another method of forming multilumen catheters. Extrusion involves pushing a melted resin through a die and into a cooling bath. The die size must be changed for each size catheter produced.
Another known process for producing multilumen catheters involves the use of platens. In this process, two or more catheter tubes are joined together and placed inside of a metal mold or platen that has an embedded shape of the catheter tubes. Typically, the platen is made of aluminum or another heat-conducting metal. Once the catheter is placed within the platen mold, the platens are then put between two heated metal plates and heated. The platens are then cooled to confer the desired shape to the catheter shaft that was placed inside of the platen molds. In another aspect, catheters can be manufactured using butt welding techniques, where at least one tube can be attached to the distal end of the catheter tubes such that the added tubes form a passageway with the catheter tubes and are in fluid communication with the added tubes.
The above described methods of manufacturing such catheters have several disadvantages. Multilumen catheter extrusion processes can be time-consuming and more costly to produce compared to single lumen catheter extrusion processes. Outer sleeves can be disadvantageous because they can be costly and more time consuming due to additional manufacturing steps. They can also add additional bulk to the catheter and may require additional steps during manufacturing. Chemical slurries or solvents can adversely affect or alter the physical properties of catheter tube materials, and in some cases, can cause the catheter tubes to degrade. They can also be difficult for a user to work with and can leave a messy residue behind that can leak or spill over the edges of the catheter tube surfaces. Such chemicals or solvents can be time-consuming, toxic, and hazardous for a user to dispose of. Chemical solvents or bonds can come apart over the course of time if the chemicals break down. There can also be a chance that the chemical solvent cannot be applied evenly or consistently to the surface of a catheter tube. This can lead to selected portions of the catheter tubes being more securely bonded than other portions, which can lead to weakness, kinking, or separation of the catheter tubes, thereby compromising the integrity of the catheter tubes and the treatment of the patient.
While platens are useful for bonding multiple catheter tubes together and conferring desired shapes to catheter shafts, the use of platens can cause the finished catheter shaft to take on the characteristics of the platen surface finish, and can cause the outer shaft of the catheter to have an undesirable surface finish, which is disadvantageous when placing the catheter into a patient's body. While extrusion techniques can produce catheters with very good surface finishes, if the catheter surface is re-heated in a platen mold, this re-heating can destroy the exterior surface of the catheter. The use of platen molds can also increase the catheter manufacturing time because a different type of platen mold is required for each catheter size and length. Butt welding techniques can be disadvantageous because the catheter tubes can become separated from the added catheter tube portions. A vascular access catheter and method of manufacturing such catheter has not yet been proposed that solves all of the above-mentioned problems.
Provided herein is an improved multilumen catheter and method of manufacturing multilumen catheters. The improved method of manufacturing the multilumen catheters described herein allows at least two catheter tubes to be consistently, reliably joined together longitudinally using a heat-bonding process, without the negative effects of chemical or solvent bonding processes, extrusion or outer sleeve processes, or the use of platen molds described above. During this process, at least a portion of at least two catheter tubes are heated and permanently joined along at least a portion of opposing internal surfaces of the catheter tubes together through an orifice of a die, to form a unitary multilumen catheter shaft.
It is a purpose of this invention to provide a catheter manufacturing process wherein the temperature of the heat used to heat at least a portion of the catheter tubes or the location of the heat can be adjusted to alter the strength of the bond between the catheter tubes. In this aspect, a permanent bond can be created between at least a portion of at least two catheter tubes, and a splittable bond can be created between at least a portion of the at least two catheter tubes.
It is a further purpose to provide a method of manufacturing that can incorporate different materials, such as wires, electrodes, or radiopaque materials, between the catheter tubes as the tubes are heat-bonded together.
It is a further purpose to provide a method of manufacturing that can be used to produce a catheter having a smooth outer surface finish for at least a portion of the catheter shaft because only a portion of the catheter inner surface is heated, and the finished outer surface portion of the catheter is not subjected to heat.
It is a further purpose to provide a method of manufacturing that can be used to produce catheter shafts having tubes with different durometers, tensile strengths, flexibilities, radiopacity, colors, lengths, outer shapes or lumen configurations, such as dual lumen or triple lumen, split tip or non-split tip, or other different properties, including splittable or peelable catheter shafts.
It is a further purpose to provide a method of manufacturing multilumen catheters that is more cost effective, faster, and safer compared to known catheter bonding methods.
Various other aspects and embodiments of the present invention will become apparent to those skilled in the art as more detailed description is set forth below. Without limiting the scope of the invention, a brief summary of some of the claimed embodiments of the invention is set forth below. Additional details of the summarized embodiments of the invention and/or additional embodiments of the invention may be found in the Detailed Description.